Enhancement: improve SL4J log level and log messages quality

[fhussonnois]

The connector seems to use the log prefix ======= in a random way leading to poor quality of logged messages. In addition, the connector seems to have a bad use of the log levels, i.e., DEBUG, TRACE, INFO for logging exception.

pubsubplus-connector-kafka-source/src/main/java/com/solace/connector/kafka/connect/source/SolaceSourceTask.java

Lines 130 to 133 in e0fcb78

	log.info(
	"================ Encountered exception in message processing....discarded."
	+ " Cause: {}, Stacktrace: {} ",
	e.getCause(), e.getStackTrace());

Unfortunately, this makes the logs difficult to analyze in a production environment and it is difficult to trace errors.